Greene County climate

Greene County Frost Dates and Growing Season

NOAA 1991-2020 normals for Siloam 3N, 8.5 km from Greene County, elevation 695 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Siloam 3N. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around March 27 and the first fall freeze around November 8, a growing season of about 226 days.

Median at 36°F
last April 9, first October 30
Median at 32°F
last March 27, first November 8
Median at 28°F
last March 12, first November 23

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FApr 28Apr 20Apr 16Apr 12Apr 9Apr 6Apr 2Mar 30Mar 23
32°FApr 13Apr 7Apr 3Mar 31Mar 27Mar 23Mar 19Mar 14Mar 6
28°FMar 31Mar 25Mar 20Mar 16Mar 12Mar 7Mar 2Feb 25Feb 17
24°FMar 19Mar 12Mar 5Mar 1Feb 24Feb 18Feb 12Feb 5Jan 28
20°FMar 5Feb 27Feb 17Feb 9Feb 4Jan 31Jan 24Jan 16Jan 5
16°FFeb 26Feb 11Feb 3Jan 31Jan 26Jan 21Jan 15Jan 8Dec 30

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 3Nov 7Nov 12
32°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 26
28°FNov 4Nov 9Nov 14Nov 19Nov 23Nov 28Dec 1Dec 6Dec 17
24°FNov 15Nov 24Nov 30Dec 3Dec 8Dec 15Dec 22Dec 30Jan 5
20°FDec 1Dec 8Dec 16Dec 24Dec 30Jan 3Jan 9Jan 16Jan 27
16°FDec 14Dec 25Jan 1Jan 5Jan 12Jan 16Jan 20Jan 28Feb 7

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F222216211207203198193188181
32°F255245237231226222217212205
28°F287276269262256250244238230
24°F322311303296289282276269257
20°F358346335330322315308300289
16°F365365365358349342334324311

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
93% of years
16°F or colder
65% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
2,861
Cooling degree days, base 65°F
1,765
Growing degree days, base 40°F
8,172
Growing degree days, base 45°F
6,562
Growing degree days, base 50°F
5,113
Growing degree days, base 55°F
3,827
Growing degree days, base 60°F
2,707

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January667043
February513156
March36810173
April15945345
May35161591
June1352801
July0460925
August0422886
September10246685
October12859402
November3847142
December597261

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 8.5 km from Greene County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00098064 (Siloam 3N). Public domain.